From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tao Ma Subject: [PATCH] ext4: Fix a BUG in mb_mark_used during trim. Date: Thu, 3 Mar 2011 17:33:52 +0800 Message-ID: <1299144832-5123-1-git-send-email-tm@tao.ma> Cc: "Theodore Ts'o" To: linux-ext4@vger.kernel.org Return-path: Received: from cpoproxy2-pub.bluehost.com ([67.222.39.38]:54013 "HELO cpoproxy2-pub.bluehost.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1753153Ab1CCJeO (ORCPT ); Thu, 3 Mar 2011 04:34:14 -0500 Sender: linux-ext4-owner@vger.kernel.org List-ID: From: Tao Ma In a bs=4096 volume, if we call FITRIM with the following parameter as fstrim_range(start = 102400, len = 134144000, minlen = 10240), we will trigger a BUG_ON. BUG_ON(start + len > (e4b->bd_sb->s_blocksize << 3)); Mar 4 00:55:52 boyu-tm kernel: ------------[ cut here ]------------ Mar 4 00:55:52 boyu-tm kernel: kernel BUG at fs/ext4/mballoc.c:1506! Mar 4 01:21:09 boyu-tm kernel: Code: d4 00 00 00 00 49 89 fe 8b 56 0c 44 8b 7e 04 89 55 c4 48 8b 4f 28 89 d6 44 01 fe 48 63 d6 48 8b 41 18 48 c1 e0 03 48 39 c2 76 04 <0f> 0b eb fe 48 8b 55 b0 8b 47 34 3b 42 08 74 04 0f 0b eb fe 48 Mar 4 01:21:09 boyu-tm kernel: RIP [] mb_mark_used+0x47/0x26c [ext4] Mar 4 01:21:09 boyu-tm kernel: RSP Mar 4 01:21:09 boyu-tm kernel: ---[ end trace 9f461696f6a9dcf2 ]--- The reason is that in ext4_trim_fs, the last_block is checked wrongly. if (len >= EXT4_BLOCKS_PER_GROUP(sb)) len -= (EXT4_BLOCKS_PER_GROUP(sb) - first_block); else last_block = first_block + len; So if len < EXT4_BLOCKS_PER_GROUP while first_block + len > EXT4_BLOCKS_PER_GROUP, last_block will be set to a overflow value which exceeds EXT4_BLOCKS_PER_GROUP. This patch fixes it and adjusts len accordingly. Cc: "Theodore Ts'o" Signed-off-by: Tao Ma --- fs/ext4/mballoc.c | 5 +++-- 1 files changed, 3 insertions(+), 2 deletions(-) diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c index 29d7d17..ed63c3e 100644 --- a/fs/ext4/mballoc.c +++ b/fs/ext4/mballoc.c @@ -4889,10 +4889,11 @@ int ext4_trim_fs(struct super_block *sb, struct fstrim_range *range) break; } - if (len >= EXT4_BLOCKS_PER_GROUP(sb)) - len -= (EXT4_BLOCKS_PER_GROUP(sb) - first_block); + if (first_block + len >= EXT4_BLOCKS_PER_GROUP(sb)) + last_block = EXT4_BLOCKS_PER_GROUP(sb); else last_block = first_block + len; + len -= last_block - first_block; if (e4b.bd_info->bb_free >= minlen) { cnt = ext4_trim_all_free(sb, &e4b, first_block, -- 1.6.3.GIT